Such a fate has already overtaken one of them, under
the very eyes of the astronomers, within the relatively
short period during which these ill-fated comets have.
been observed. In 1832 Biela's comet passed quite
near the earth, as astronomers measure distance, and in
doing so created a panic on our planet. It did no
greater harm than that, of course, and passed on its
way as usual. The very next time it came within telescopic
hail it was seen to have broken into two fragments.
Six years later these fragments were separated
by many millions of miles; and in 1852, when the comet
was due again, astronomers looked for it in vain. It
had been completely shattered.

What had become of the fragments? At that time
no one positively knew. But the question was to be
answered presently. It chanced that just at this period
astronomers were paying much attention to a class of
bodies which they had hitherto somewhat neglected,
the familiar shooting-stars, or meteors. The studies of
Professor Newton, of Yale, and Professor Adams, of
Cambridge, with particular reference to the great
meteor-shower of November, 1866, which Professor Newton
had predicted and shown to be recurrent at intervals
of thirty-three years, showed that meteors are
not mere sporadic swarms of matter flying at random,
but exist in isolated swarms, and sweep about the sun
in regular elliptical orbits.